In the manufacture of shingles, it has been known that when shingles are subjected to strong winds, the winds can engage the lower edges or tab portions of the shingles, and bend them upwardly.
On occasion, under strong winds, the tabs can bend upwardly in amounts sufficient that the inherent. Internal resistance to substantial bending and perhaps cracking, can be overcome, in that the mat that is formed internally of the shingle, and the asphaltic material on the surfaces of the shingle, may not be sufficient to withstand certain wind conditions.
Various approaches have been made to resist shingle failure via cracking and the like, not all with substantial success.
For example, strips of adhesive material along lower ends of tabs of shingle have been applied, which, when subjected to hot weather conditions, soften an amount sufficient that such adhesive will adhere to the next-subjacent shingle on a roof, eventually harden and thereafter resist upward deflection of shingle tabs under severe wind conditions. However, such adhesive sometimes dries out, or becomes brittle over time, offering reduced adhesion. In other cases, strong wind conditions can exist during high temperature situations when such adhesive located under tabs remains soft, and thus the adhesive does not function in its intended manner.
Other approaches have resorted to thickening the mat and/or asphaltic material, to offer internal resistance to bending, hut nonetheless, failures due to wind-related bending of tabs of shingle continue to exist.